golang: Update to 1.13.7, add PKG_CPE_ID to Makefile

This update includes fixes for[1]:
* CVE-2020-7919 - doesn't appear to be published publicly yet
* CVE-2020-0601 - a Windows-related issue

[1]: https://github.com/golang/go/issues?q=milestone%3AGo1.13.7+label%3ACherryPickApproved



Signed-off-by: Jeffery To <jeffery.to@gmail.com>